1. Field of the Invention
The present invention relates generally to a wireless telecommunication, and more particularly to a method of controlling the connection of a station to different access points in roaming.
2. Description of the Related Art
Because of the popularity of the application of wireless telecommunication, more and more people use wireless telecommunication for connection to network, communication by phone, or data transmission. Typically, the station at user end usually transmits data through wireless communication with access points (AP). However, the coverage of each AP is limited that the station far away from the AP may not receive the signals and loss the connection with the AP when there is only one AP in a large area or in buildings.
Therefore, it must provide several APs in a large area or in buildings that the station may keep the connection with the AP in roaming to avoid unexpected disconnection.
The roaming still has some drawbacks. For example, the station will cut the connection with the original AP off first when it senses a weak signal therebetween, and then, scan the signal strengths of the APs in each channel. Take IEEE 802.11g for example, the client end has to scan eleven channels in sequence. Suppose that it needs 0.1 second to scan one channel, it will take more than 1.1 seconds to finish the scan of the eleven channels. Besides, it still needs to authenticate or exchange pairwise key through 4-way hand shaking to complete the connection to a new AP after scan. It is obvious that the conventional device needs much of time in roaming and it might lead to delay of the data transmission, especially relative to the real-time application, such as voice and multimedia transmission application.
An improved network based on control and provisioning of wireless access points (CAPWAP) provides an access controller (AC) to manage the APs and scan the signal strength of the signals received from the APs. However, it still needs time for authentication, or pairwise key exchange through 4-way hand shaking which means that it still delays the data transmission in moaning.
In conclusion, it still needs to improve the conventional connection control.